This invention relates to a suspended ceiling grid structure having cross tees and main beams that support ceiling tiles, or other ceiling surfaces. A ceiling of this type is shown in U.S. Pat. No. 4,785,603. Such structure is suspended from a structural ceiling, or structural bars or ceiling joists, by hanger wires. The weight of the grid structure and tiles, or other surface, keeps the hanger wires in tension, and no downward movement is generally possible.
The wires do not, to any substantial degree, resist upward movement of the grid, or compression of the wires, so that it is possible for the ceiling or segments thereof to move upward under the influence of upward forces in the ceiling.